Camera crane

ABSTRACT

A camera crane has a boom arm pivotably connected to a post assembly. The boom arm is extendible via an extension accessory kit. A track section is pivotably attached to the front end of the boom arm, and is leveled via leveling rods. The boom arm has a joggled section to provide clearance for a camera operator. A camera frame carrying a camera is linearly moveable along the track section. Pivot joints provide for adjustable drag on pivoting movement, without backlash or slip/stick movement. The track section is provided with a track frame and a slide head, so that the track section can be used apart from the crane.

BACKGROUND OF THE INVENTION

[0001] This Application is a Continuation-in-Part of Ser. No.09/616,587, filed Jul. 14, 2000, and now pending, which is aContinuation-in-Part of Ser. No. 09/584,561 filed on May 31, 2000, nowpending, and incorporated herein by reference.

[0002] The field of the invention is camera cranes.

[0003] Camera cranes are often used in motion picture and televisionproduction. The motion picture or television camera is typically mountedon a crane arm supported on a mobile base, dolly, or truck. The mobilebase may be pushed and steered by hand. Larger units, which have moreweight carrying capacity, and longer reaches, typically have electricdriving motors powered by onboard batteries. Some mobile bases may alsoserve as over the road vehicles.

[0004] Camera cranes generally have a crane arm supported on a base,with a camera platform at one end of the arm, and a counter weight atthe other end. The crane arm can be pivoted by hand to raise and lowerthe camera, and also to pan to the left or right side. A leveling systemis often included to maintain the camera platform in a levelorientation, as the camera platform is raised and lowered.

[0005] With the development of high definition digital, televisioncameras, and remote controlled motion picture cameras, filming can beachieved with or without a camera operator behind the camera. Rather,the remotely-controlled camera may be suspended on a crane arm, with thecamera operator monitoring the image captured by the camera via a remotemonitor, rather than a view finder in the camera. Still, most filming isperformed with the camera operator, cinematographer, director, or otherperson behind the camera, so that the recorded image is viewed in theviewfinder of the camera, and not on a remote monitor.

[0006] Due to the variety of filming or video locations, the cameracrane arm should advantageously be portable and lightweight. On theother hand, the arm must be rigid enough, when assembled, to resistbending and sagging, and to avoid excessive whipping motion of thecamera during crane arm movement.

[0007] Mobile bases with crane arms supporting a camera are frequentlyalso used in the television production of sporting events, concerts, andother televised or filmed events. While various camera cranes have beenwidely known and successfully used, certain disadvantages remain. Onedisadvantage is that the presence of the crane structure around thecamera can interfere with the camera operator, cinematographer,director, etc., e.g., by preventing them from taking a desired position,usually behind the camera. Another disadvantage is the time required toset up a camera crane. Typically, camera cranes are provided in sectionswhich must be bolted together to make a boom arm of a desired length.This requires time, tools, and skill. As production time is usuallyextremely expensive, even small time savings may be significant.

[0008] Accordingly, there is a need for an improved camera crane. Thereis also a need for an improved camera crane which is light weight andeasily transportable, but yet which can steadily carry significantpayloads, and which can position and support a camera in a wide range ofpositions and orientations, while also avoiding excessive interferencewith the camera operator. There is a further need for a camera cranewhich can be quickly and easily set up, preferably without the need fortools.

SUMMARY OF THE INVENTION

[0009] To this end, a camera crane includes a boom arm pivotallyconnected to a post assembly adapted to be supported on a camera dolly.A track section is attached at the front end of the boom arm, and acounter weight platform is attached at the back end of the boom arm.Leveling rods extending between the track section and counter weightplatform to maintain the track section and counter weight platform in ahorizontal orientation, as the boom arm is pivoted or tilted up anddown, to change the elevation of the camera. A camera frame is linearlymovable along the track section. As a result, the camera can be easilymoved into a wide range of positions.

[0010] In a second and separate aspect of the invention, the boom armhas a joggle section, to provide additional head room clearance aroundthe camera.

[0011] In a third and separate aspect of the invention, the camera frameis rotatably supported on the track section, so that the camera can pancontinuously in either direction, clockwise or counter-clockwise.

[0012] In a fourth and separate aspect of the invention, a cameraplatform is pivotally or rotatably attached to the camera frame. Thecamera is attached to the camera platform. As a result, the camera cancontinuously change elevation angle, with the camera lens positioned,e.g., vertically straight up or straight down, and at any angle inbetween.

[0013] In a fifth and separate aspect of the invention, and counterweight platform and counter weights are concave with a rounded backsurface, to minimize the clearance space needed to turn the boom arm,while providing an extended range of camera lens height.

[0014] In a sixth and separate aspect of the invention, andanti-backlash or motion control pivot joint or device is provided on theboom arm and camera frame, to provide for smooth dampened back lash freemovement.

[0015] In a seventh and separate aspect of the invention, a lightweightone piece camera crane is provided which can be quickly set up withouttools.

[0016] In an eight and separate aspect of the invention, a track sectionon the crane can be quickly removed and replaced with an accessory toprovide different camera mounting positions and a more compact andlightweight design.

[0017] In a ninth and separate aspect of the invention, roll movement isprovided via an alternative camera frame design or via a roll movementaccessory attached to a camera a base plate supported by the crane.

[0018] The invention resides as well in sub combinations of the featuresas described below.

[0019] Additional features and advantages will appear hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the drawings, wherein the same reference number indicates thesame element, throughout the several views:

[0021]FIG. 1 is a perspective view of the present camera crane mountedon a camera dolly, with the crane boom arm in an elevated position;

[0022]FIG. 2 is a perspective view thereof with the boom arm in alowered position;

[0023]FIG. 3A is a side elevation view of the boom arm shown in FIGS. 1and 2;

[0024]FIG. 4A is a section view taken along line 4A-4A of FIG. 3A;

[0025]FIG. 5A is a section view taken along line 5A-5A of FIG. 3A;

[0026]FIG. 3B is an enlarged view of the track section shown in FIGS.3A;

[0027]FIG. 4B is an enlarged view of FIG. 4A;

[0028]FIG. 5B is an enlarged view of FIG. 5A;

[0029]FIG. 6 is a plan view of the camera crane of FIG. 3A;

[0030]FIG. 7 is an enlarged section view of the anti backlash jointsshown in FIG. 3A;

[0031]FIG. 8 is a front view, in part section, or an alternative cameraframe for use with the crane shown in FIG. 3A;

[0032]FIG. 9 is a side view of the camera platform support plates shownin FIG. 8;

[0033]FIG. 10 is a plan view of a vibration isolator for use with thecamera crane shown in FIGS. 1-3A;

[0034]FIG. 11 is a side view thereof;

[0035]FIG. 12 is a top view of mounting block for use with a removabletrack section;

[0036]FIG. 13 is side of a removable track section;

[0037]FIG. 14 is front end view of the removable track section installedon the crane shown in FIGS. 1-6;

[0038]FIG. 15 is a top view of an accessory for providing roll movement;

[0039]FIG. 16 is a side view of the accessory shown in FIG. 15;

[0040]FIG. 17 is a side view of another accessory;

[0041]FIG. 18 is a side view of an alternative boom arm, including anextension section;

[0042]FIG. 19 is a top view thereof;

[0043]FIG. 20 is a side elevation view of a leveling rod for use withthe boom arm shown in FIGS. 18 and 19;

[0044]FIG. 21 is a top view thereof;

[0045]FIG. 22 is an end view of a track section accessory, which may beattached directly to the platform of a camera dolly, such as the cameradolly shown in FIG. 1, or to other dollies or cranes;

[0046]FIG. 23 is a side view thereof;

[0047]FIG. 24 is a top view thereof;

[0048]FIG. 25 is an end view of the track section frame shown in FIGS.22-24;

[0049]FIG. 26 is a side view thereof;

[0050]FIG. 27 is a top view thereof;

[0051]FIG. 28 is an end view, in part section of the slide head shown inFIGS. 22-24;

[0052]FIG. 29 is a side view thereof; and

[0053]FIG. 30 is a top view thereof.

DETAILED DESCRIPTION

[0054] Turning now in detail to the drawings, as shown in FIGS. 1 and 2,a camera crane 40 is supported on a dolly platform 28 of an arm 26 of acamera dolly 20. The dolly wheels 24 and arm 26 are attached to a dollychassis 22. The camera dolly is described in detail in U.S. patentapplication Ser. No. 09/055,012, and U.S. Pat. No. 4,360,187,incorporated herein by reference.

[0055] Referring to FIGS. 1-3A, the crane 40 includes a boom arm 44pivotally supported on a post assembly 42. The post assembly 42 ispivotably attached to a head frame 124 which is connected to the dollyplatform 28. The head frame includes a leveler 132 having jack screws orother leveling devices, such as described in U.S. Pat. No. 6,086,207,incorporated herein by reference. The leveler 132 allows the entirecrane 40 to be leveled with respect to the dolly platform 28.

[0056] The boom arm 44 is pivotally connected to the post assembly 42for vertical movement at a boom arm center pivot joint 46. A pair ofleveling rods 48, are spaced apart on either side of the boom arm 44.The leveling rods 48 are also pivotally attached to the post assembly 42at leveling rod center pivot joints 50.

[0057] A counter weight platform 52 is pivotally attached to the boomarm 44 at a boom arm rear pivot joint 54. The leveling rods 48 aresimilarly attached to the counter weight platform at leveling rod rearpivot joints 56.

[0058] A track section 60 is rigidly attached to a track section arm 62.The track section arm 62 is pivotally attached to the front end of theboom arm 44 at a boom arm front pivot joint 64. The leveling rods 48 aresimilarly pivotally attached to the track section arm 62 at leveling rodfront pivot joints 66.

[0059] Referring still to FIGS. 1-3A, the boom arm 44 has a rear segment80 which is parallel to the leveling rods 48, and which is horizontal,when the boom arm 44 is horizontal. A first front segment 82, secondfront segment 84, and third front segment 86 are joined together, withthe third front segment 86 also joined to the rear segment 80. As shownin FIG. 3A, the third front segment 86 is joined at a rise angle to therear segment 80. The angle θ is generally from 15-45°, and preferablyabout 30°. The second front segment 84 is joined to the first frontsegment 82 at an angle supplementary to angle θ, so that the secondfront segment 84 is parallel, but vertically offset, from the rearsegment 80. The third front segment 86 is likewise joined to the secondfront segment 84 at angle negative θ. The first front segment 82preferably is of the same length as the third front segment 86, so thatthe upward rise resulting from the inclined third front segment 86 isequally offset by the decline of the first front segment 82. As aresult, the pivot joints on the boom arm 44, i.e., the boom arm rearpivot joint 54, the boom arm center pivot joint 46, and the boom armfront pivot joint 64, are all aligned on the center line C-C. However, ahead room space, generally designated 45 in FIG. 3A, is formed betweenthe boom arm 44 and the floor. As a result, the camera operator hasadditional vertical clearance space or head room, extending from line Dto the bottom surface of the boom arm 44.

[0060] The segments 80, 82, 84 and 86 are preferably formed from analuminum 4″×4″ square beam tube extrusion, having a ¼ inch wallthickness, wedge cut to form the angle joints which are pressed closed,and then welded. To reduce weight, the central areas of the sides, topand bottom surfaces of the boom arm 44 are reduced in thickness, formingrelieved wall sections 88, on all surfaces. In addition, lighteningholes 90 are advantageously provided along the center lines of each ofthe front segments, on the sides, top and bottom. The relieved sections88 are preferably made by reducing the wall thickness of the box beamused to form the boom arm 44 from ¼ inch to ⅛ inch, thereby reducing theweight of the boom arm 44 by almost 50%. The metal thickness at theedges is retained for improved rigidity and weld strength. As themajority of the surfaces of the boom arm are relieved areas, they haveincreased protection against scratches and other damage.

[0061] Referring to FIG. 3A, the counter weight platform 52 is formed bya bottom plate 102 and a front wall 104. A weight post 112 extendsvertically upward from the bottom plate 102. Counter weights 106 arestacked onto the counter weight platform 52, with the post 112 extendingthrough clearance holes in the counter weights 106. As shown in FIG. 6,the counter weight 106 have a radiused back surface 108. This allows theboom arm 44 to pivot about on the dolly platform 28 with a minimum ofclearance.

[0062] As shown in FIG. 3A, the bottom plate 102 also has a forwardlycurving relieved section 110, to allow the counter weight platform 52 tobetter clear the dolly steering handle 30, as shown in FIG. 2, when thehandle is at 90°. Also, as show in FIGS. 3A and 6, the camera frame 68is rotatably attached to a frame slider plate 70 which is slidableforward and back on the track section 60.

[0063] Referring to FIG. 4B, the post assembly 42 includes spaced apartslide plates 120 attached to a base collar 122 via bolts 125. The basecollar 122 is rotatably supported on an axle 126, via an upper bearing130 and a lower bearing 128. The axle 126 is bolted on to the head frame124, which in turn is secured to an upper plate or structure of theleveler 132. A lower section of the leveller is attached to the dollyplatform 28 with a threaded knob 32. A crane pan pivot joint 140 islocated between the side plates 120 and on top of the axle 126. Thecrane pan pivot joint 140 adjusts the drag or braking force whenpivoting the crane 40 about the head frame 124 and camera dolly platform28. Lateral stubs 50 extend outwardly from the top ends of the sideplates 120, to support the leveling rod center pivot joints 50. A key225 irrotatably secures the cap plate 230 to the axle 126.

[0064] As shown in FIGS. 3, 5B and 6, the track section 60 includes twosquare track tubes 162 attached to and extending parallel and forwardfrom the track section arm 62. The track tubes 162 are preferably madeof stainless steel two inch by two inch square tubes with a 0.083 wallthickness. The track section 62 includes left and right arm assemblies72 and 74 fixed to and joined by a cross shaft 75. Each of the armassemblies 72 and 74 includes inner and outer plates 76 and 78, with theleveling rod front pivot joints 66 positioned between the inner andouter plates from both the left and right arm assemblies 72 and 74, asshown in FIG. 5B.

[0065] Referring still to FIG. 5B, the frame slider plate assembly 70 isslidable front to back on track bearing rails 164 attached to the insideof each track tube 162, via rail bolts 170. Bearing blocks 166 areattached to the slide plate 190 with fasteners 192. Clearance holes 172are provided on the outside of the track tubes 162, to access to bolts170. A linear rod bearing 168 is secured within the bearing block 166,on each side, and allows the frame slider plate assembly 70 to slidefront to back on the track bearing rails 164 with low friction. Thetrack section 60 in the embodiment shown allows for 24 inches of slidinghorizontal linear travel. The back ends of the track rails 164 areattached to a bridge plate 165 extending between the track tubes 162 atthe back end of the rail section 60. The front ends of the track tubes162 are attached to the front end plate 204.

[0066] A frame slider plate assembly drag adjuster 180 on the slideplate 190 has a bushing 186 on the tip of a thumb screw 182 threadedinto the slide plate 190. A spring 184 urges the bushing 186 outwardlyinto sliding engagement against the track bearing rail 164. The slidingfriction of the frame slider plate assembly 70 along the track bearingrails 164 is adjusted by turning the thumb screw at 182, which increasesor decreases the spring engagement force of the A bushing 186 againstthe track bearing rail 164. The slide spring plate 190, and thus thecamera frame 68, can be locked in place on the track bearing rails 164by sufficiently tightening the thumb screw 182.

[0067] A plate collar 194 is fixed within a central opening of the slideplate 190, and extends downwardly from the slide plate 190. A track axle198 is rotatably supported within the plate collar 194 by upper andlower bearings 196. The drag force on rotation of the track axle isadjusted with a track axle pivot joint 200.

[0068] Tension wires 206 optionally extend from the end plate 204 to theleft and right arm assemblies 72 and 74, as shown in FIGS. 1 and 2.

[0069]FIG. 7 shows the detailed construction of the non-slip/stick dragor pivot joints 210 used on the crane 40. The joint 210 shown in FIG. 7is preferably used for all pivot joints on the crane 40 which haveadjustable tension or drag features, specifically, the crane pan pivotjoint 140 shown in FIG. 1B, the boom arm center pivot joints 46 (leftand right) shown in FIG. 4B, and the camera frame pivot joint 160, asshown in FIG. 5B. While the Figures show other optional designs for thejoints 140, 46, and 160, the joint construction shown in FIG. 7 ispreferred for all such joints.

[0070] Turning in detail to FIG. 7, a stud section 222 of a hand knob220 is threaded into an axle 224 forming a tensioner 223. The axleextends through an outer hub 252 and an inner hub 254 and is clamped inplace by a hub nut 256. A needle thrust bearing 226 under the hand knob220 press against a compression washer 228, which in turn presses on afloating cap plate 230, as the hand knob 220 is tightened. Other formsof tensioners, such as cams, levers or springs, may also be used inplace of the hand knob and screw threads, to adjust drag joint friction.

[0071] An arm plate 236 is positioned between the flex plate 232 andaxle hub 245 secured to the outer hub 252 via a pin 260. The arm plate236 has arms 240 extending out from opposite sides of a ring section238. The arm plate 236 is pivotally or rotatably positioned over a hubsection 247 of the axle hub 245, on a DU bushing 246. A stack of Teflonrings 234 are contained within the flex plate 232, and are compressedbetween the flex plate 232 and the upper surface of the ring section 238of the arm plate 236. Similarly, a stack of lower Teflon rings 242 arepositioned between the lower surface of the ring section 238 of the armplate 236, and a receiving groove 249 formed in the upper surface of theaxle hub 245.

[0072] The flex plate 232 is attached to the axle hub 245 via fasteners235. The arms 240 of the arm plate 236 are attached to the movingsection, such as the boom arm 40 by clamping screw 250 extending intostandoffs 248. The moving section, such as the boom arm is pivotally orrotatably supported on the hub bearing 258 on the outer hub 252 andinner hub 254.

[0073] A heavy grease 265 is provided between each of the rings 234 and242, as well as between the top ring and the flex plate, and the bottomring and the receiving groove 249, to further reduce friction.

[0074] Referring still to FIG. 7, the arm plate 236 pivots or rotateswith the moveable section, such as the boom arm 40 or the track axle198, while the other components remain fixed in place.

[0075] The drag or braking force of the pivot joint 210 is adjusted byturning the hand knob 220. As the hand knob 220 is tightened down, thefloating cap plate 230 presses down and deflects the flex plate 232slightly, increasing the normal force clamping the flex plate 232,Teflon rings 234 and 242 and arm plate 236 together, thereby increasingthe drag force. The flex plate has an annular undercut area 233 whichallows the flex plate to deflect under clamping force from the cap plate230. The deflection is generally up to 0.006 inches. When the arm, orother moveable component using the pivot joint is brought to a stop,there is no backlash, stick-slip, or other force tending to move the armout of position, as can occur with other types of pivot joints.

[0076] Referring to FIGS. 3A and 5B, the camera frame 68 is rigidlyattached to the track axle 198 in the frame pivot joint 160. This allowsthe camera frame 68 to pivot or rotate, as well as translate in and outalong the track section 60.

[0077] As shown in FIG. 3A, the camera frame 68 includes a U-section 270suspended from the track axle 198. A base plate 272 is pivotallysupported on each of the arms 271 and 273 of the U-section 270, via handgrip joints 276. The hand grip joints 276 preferably have the sameconstruction as the other pivot joints, such as the frame pivot joint160 and the boom arm pivot joint 46, which construction is shown in FIG.7. However, hand grips 274 are threaded into a hub 278 attached to thecamera platform 272. Turning the hand grips 274 tilts the cameraplatform up or down, while turning the knobs 220 sets the drag orfriction on such tilting movement.

[0078] The figures are draw in proportion and to scale and generallyaccurately show the relative sizes and positions of the componentsdescribed. As shown in FIG. 3A, the U-section 270 has a width ofapproximately equal to the length of the rear segment 80. This widthprovides space for mounting a wide variety of cameras, and includesvertical clearance for a film magazine 279, and a viewfinder on thecamera 275. The distance between the center line H-H of the hand gripjoints 276 and the base plate 272 is set so that the line H-H passesthrough the center of gravity of the camera. Consequently, the baseplate 272 is preferably attached to the U-section 270 so that thespacing between the plate 272 and line H-H can be quickly and easilychanged, e.g., via slotted holes, etc. By setting the center of gravityof the camera 275 on line H-H, no moment is generated tending to changethe elevation angle of the camera lens 277, regardless of the elevationangle. Consequently, if desired, the hand grip joints 276 can be set tovirtually no drag force, without having the camera drift or shiftinadvertently in elevation.

[0079] Referring to FIGS. 2-3A in use, a camera 250, such as a video,television or motion picture film camera 275 is mounted on the baseplate 272, with the center of gravity of the camera 275 on line H-Hpassing through the hand grip joints 276. With the crane 40 attached ontop of a dolly platform 28 of a camera dolly 20, counter weights 106 areadded on to the counter weight platform 52, until the boom arm 44 isbalanced. This balancing may be performed with the camera frame 68 atany position along the track section 60. The distance between the boomarm front pivot joint 64 and the boom arm center pivot joint 46, in theembodiment shown, is twice the distance between the boom arm centerpivot joint 46 and the boom arm rear pivot joint 54. Of course, otherratios may be selected. While the short length of the crane 40 behindthe post assembly 42 provides for a more compact and versatile design,it requires counter weights 160, even with no camera pay load on thecamera platform 272. In the embodiment shown in the drawings, with nocamera payload, the boom arm 42 is counterbalanced with about 95 poundson the counter weight platform 52. Payloads may range from 10-100 lbs.with a preferred maximum of about 60 lbs.

[0080] To set up the crane for use, the camera is attached to the cameraplatform 272. Counter weights 106 are added until the arm is balanced,preferably with the crane in a horizontal position. Referring to FIG.3A, once the crane is balanced, it will remain balanced, regardless ofthe in/out position of the camera frame 68. Although the center ofgravity of the entire crane 40 will change with in/out movement of thecamera frame 68, the arm 44 will remain balanced. This occurs becausethe downwardly vertical force acting through the joint 64, resultingfrom the weight of the camera frame 68 (and the entire track section 60)does not change as the camera frame 68 moves in and out. The momentexerted about the joint 64 changes with movement of the camera frame 68and its camera payload. Consequently, with the camera frame 68 at thevery front or out position, next to the end plate 204, the moment actingabout the joint 64 is at a maximum. However, this moment is countered bythe tension in the leveling rods. As the vertical force actingdownwardly through the pivot joint 64 remains unchanged, the boom armremains balanced, regardless of the front to back movement of the cameraframe 68. Thus, after the boom arm is balanced, it will remain balanced,regardless of the movement or position of the camera frame 68 and thecamera payload. Bubble levels 55 attached to the boom arm may be usedfor the initial leveling step.

[0081] As the boom arm moves from horizontal towards a more vertical upor down position, less force is required to counter balance the weightof the pay load, and the weight of the boom arm forward of the joint 46.This occurs because as the arm moves from horizontal to vertical, thestresses change from bending to compressive stresses. As a result, theshape of the arm changes slightly, and it becomes straighter. As the armbecomes straighter, the distance between the pivot joint 46 and thecenter of gravity of the load forward of the joint 46 decreases, so thatless counterweight is needed. An arm spring 58 extending between therear segment 80 and the post assembly 42 is preferably provided, tocompensate for the reduced counter weight load needed as the boom arm 42moves away from a horizontal position. The force applied by the spring58 is minimal when the boom arm is horizontal. The force exerted by thespring 58 increases as the arm moves away from horizontal, with thespring force always acting to return the boom arm to horizontal.

[0082] The pivot joints, i.e., the crane pan pivot joint 140, framepivot joint 160, boom arm pivot joint 46, and hand grip joints 276, aretightened to provide the desired degree of drag, which may vary fordifferent applications, and according to the camera operator's personalpreferences. For example, for prolonged filming with the camera lensfixed in a specific position, the joints may be tightened, to preventany inadvertent movement of the lens 277, caused, for example, by airmovement, vibrations, etc. On the other hand, where frequent, constant,or rapid camera movements are required, the pivot joints may be set withminimal drag.

[0083] The camera frame 68 can be moved in or out to different positionsalong the track section 60. If the camera lens 277 is perfectlyhorizontal (level) with the camera frame 68 at the mid-point of thetrack section 60, the lens 277 will experience a slight decline in angleas the camera frame 68 is moved out to the front end 61 of the tracksection. This occurs because the track section 60 tips down slightlyunder the added moment resulting from the pay load at the front end 61of the track section 60. The downward deflection is caused primarily bycompression of the wheels or tires 24 on the dolly 20, under the addedload. Similarly, if the camera frame 68 is moved all the way back,adjacent to the track section arm 62, the relative reduction in loadwill cause the track section 60 to rise slightly, from back to front, sothat the lens angle is now above horizontal. Again, this resultsprimarily from the elasticity material characteristics of the wheels.The boom arm 42 itself, including the track section 60 have relativelyhigh bending moments of inertia, relative to the pay loads carried.Consequently, although they of course deflect slightly with changes inpay load position, their contribution to the change in camera angle asthe camera frame 68 moves in and out, is minimal.

[0084] Referring to FIG. 3B, to compensate for the unwanted change incamera angle as the camera frame 68 moves along the track section 60,the track bearing rails 164 are preferably provided with a slight convexcurvature. This convex curvature is preferably provided by deflectingthe track bearing rails 164 to the desired curvature (with e.g., apress), and then tightening the rail bolts 170, shown in FIG. 5B, toclamp and hold the track bearing rails 164 into the desired curvature.As shown in FIG. 3B, this is achieved by having a second set of interiorthrough holes 171 in the inside wall of the track tubes 162, with theholes 171 located on a very large radius R to hold the track bearingtubes 164 into the convex curvature. The curvature of the rails 164 inFIG. 3B, shown in dotted lines, is greatly exaggerated, for purposes ofillustration.

[0085] With the track bearing rails 164 curved into the radius asdescribed above, the camera 275 is leveled with the camera frame 68 atthe center of the track section 60. Then, when the camera frame 68 ismoved out to the front end 61 of the track section 60, the frame sliderplate is located on a slightly inclined section of the radius, whichordinarily would cause the camera elevation angle to rise. However, theadded moment or load resulting from the camera frame 68 at the end ofthe track section 60 causes the dolly wheels to deflect and compress,which along with the slight additional amount of strain in the metal ofthe boom arm 44 results in the camera elevation angle remainingsubstantially unchanged. Similarly, when the camera crane 68 is movedback adjacent to the track section arm 62, the reduced load on the dollywheels and boom arm 40 would ordinarily cause an increase in cameraangle elevation. However, as the frame slider plate 70 is now on a“downhill” section of the radius of the track bearing rails 164, thecamera elevation angle remains substantially unchanged. As a result, thecamera frame 68 may be moved to any position along the track section 60,without significantly changing the camera elevation angle.

[0086] The radius is preferably large, as only a slight amount ofdeflection occurs with movement of the camera frame 68 along the tracksection 60. Preferably, the radius ranges from 400-1200 inches, morepreferably, about 600-1000 inches, and more preferably from 750-850inches. In the specific embodiment shown in the figures, radius is 812inches. The desired value of the radius R will of course vary with thedeflection characteristics of the wheels or tires 24 and of the boom arm42. The radius R may be matched to the dolly and crane 40 by settingthem up for actual use; placing a load on the camera frame to simulatethe weight of the a camera; and leveling the boom arm with the railsinitially straight. The rails are then set at an estimated radius, e.g.,800 inches. A level indicating device, such as a laser is attached tothe camera platform, and the frame 68 is moved to the front and to theback of its range of travel, while observing the level indicator. If thelevel rises at the back and declines at the front, then more curvatureis needed. The fasteners 170 are loosened, the rails 164 are pressedinto a tighter curve to reduce R, the fasteners retightened, and thelevel testing is again observed. This process may be repeated until thechange in level of the camera platform from the front of the rails tothe back, is reduced to an acceptable amount.

[0087] Referring to FIGS. 1-3, the boom arm 44 can pivot about the boomarm center pivot point 46 by about plus or minus 60 degrees. Many knowncrane or boom arms have undesirable pinch or shear points between theirmoving parts. As a result, a crane operators hands or arms, or otherpieces of equipment such as cables, can be caught in the pinch points.However, the boom arm 44 avoids such pinch points, via the geometry ofthe leveling rods 48 and their attachment points. Specifically, as shownin dotted line in FIG. 3, with the arm 44 in the maximum up position,the upper end of the front wall 104 of the counter weight platform 52comes close to the top surface of the rear segment 80, at location P.However, sufficient clearance remains so that an operator's hand cannotbecome trapped between the moving parts. Similarly, at the front end ofthe boom arm 44, at location Q in FIG. 3, clearance space remainsbetween the leveling rods 48 and the track section arm 62, to preventtrapping an operators hand, cables, or other objects. Potential pinchpoints are reduced via the offset design of the leveling rods 48. Asshown in FIG. 3A, the leveling rods are offset to the sides of the boomarm 44, reducing pinch points. In addition, as shown in FIG. 3A, theleveling rods 48 extend beyond the height of the boom arm 44 by only aslight amount, generally equal to one half of the height or diameter ofthe leveling rods 48. This reduces the space taken up by the crane 40,providing a more compact design which is advantageous for use in tightspaces, and for shipping. Crane movement due to wind is also reduces bythe reduction in cross section achieved by the location of the levelingrods 48.

[0088] The non-tensionable or adjustable pivot joints, such as theleveling rod rear pivot joint 56 and front pivot joints 66 and the boomarm front pivot 64 are preferably provided with Teflon washers andneedle bearings, for smooth, quiet and low friction pivoting movement.Stop pads 300 made of open cell urethane foam, or sorbathane foam areprovided at the hard stop points of the boom arm 42, and at the frontand the back ends of the track section 60. The pads 300 prevent a metalto metal stop at the limit of pivoting or linear travel. The open cellpolyurethane foam, or sorbathane foam is preferred, because itcompresses to dampen and absorb movement, but exerts very little kickback or press back force. Consequently, even at the limits of travel,there is no slip/stick movement and little or no backlash, i.e.,inadvertent movement in an opposite direction. Vertical boom travelstops are similarly provided by a pad 500 on the post assembly 42

[0089] Referring to FIGS. 1-3, with the crane 40 mounted on the cameradolly 20, the dolly 20 can be maneuvered in any direction to positionthe camera 275 as desired. In addition, the arm 26 of the camera dolly20 may be raised to change the elevation of the camera 275. The crane 40itself also provides for a wide range of movements. These movementsinclude panning movements left and right 360+about the crane pan pivotjoint 140; tilt up or down, +/−about 60 degrees from horizontal, aboutthe boom arm center pivot joint 46; linear travel in and out +/−12inches, along the track section 60; pan left or right 360 degrees+,about the frame pivot joint 160; and tilt up or down in elevation 360+,about the hand grip joints 276.

[0090] Turning to FIG. 8, an alternative camera frame embodiment 280provides all of the movements described above, as well as a roll left orright+/−60 degrees. The other components of the crane 40 are asdescribed above. However, instead of the camera frame 68 having aU-section 270 suspended on the track axle 198, and outer roll housing284 is attached to the track axle 198. The semicircular roll tube 286extends from a left roll tube end bearing 288 at the left hand grip 274,through curved linear bearings 292 within the outer roll housing 284,and to a right side roll tube end bearing 288 at the right hand grip274. A roll tube extension bar 285 is attached to the roll tube 286.Extension bar riser plates 284 are attached to the hand grip joints 276and to the extension plate 285.

[0091] As shown in FIG. 9, a side plate 290 is connected to the handgrip joints 276 and to the base plate 272, and is dimensioned to placethe center of gravity of the camera 275 on line H-H.

[0092] The roll embodiment 280 shown in FIG. 8 operates in the same wayas the embodiment of FIGS. 1-3, except that the camera platform 272 canalso roll left or right. Preferably, the center of gravity of the camera275 is also positioned on the center line J of the frame pivot joint160, so that the torque required to roll the camera remains constantthroughout the roll movement. A drag adjuster 180 may also be providedon the outer roll housing 284, to adjust the drag of the roll movement.The center of gravity of the camera 275 and plate 272 are preferably setso that the radius RR from the center of gravity to the roll tube 286does not change with roll movement. Consequently, the torque needed forroll movement remains constant regardless of the position of the cameraand platform.

[0093] In most applications, the camera frame 68 or 280 will besuspended below the track section 60 on the track axle 198. However, foradded lens height, the camera frame 68 or 280 may be unbolted from thebottom of the track axle, turned upside down, and then bolted on to ariser hub 202, as shown in FIGS. 3B and 8, so that the entire cameraframe 68 or 280 is now above the track section 60. The camera 275 mayremain attached to the top surface 281 of the base plate 272, so thatthe camera becomes upside down. The camera may then be righted byrotating the handles 274 to pivot the camera platform 272. The camera275 is then positioned right side up, above the track section 60.

[0094] Referring to FIG. 2, the arms 271 and 273 of the U-section 270are subject to low amplitude vibrations in the side to side, orleft/right direction. To provide a more stable support for the camera275, a vibration isolator 400, as shown in FIGS. 10 and 11, may be usedwith the U-section 270. The vibration isolator 400 includes a cameramounting plate 402 within a frame 404. The camera mounting plate 402 ismoveable only in the side to side (left/right) direction. The cameramounting plate 402 is supported within the frame 404 via linear bearings405 formed by ball bearings 418 within a semi-circular frame groove 414in the frame 404, and a semi-circular plate groove 412 in the oppositeedges of the plate 402. Ball springs 416 at the ends of the braces keepthe ball bearings 418 centered. Return springs 408 are held withinspring bores 410 in the lateral sides of the frame 404 and plate 402.Open cell polyurethane foam 106 is provided in the lateral spacesbetween the plate 402 and frame 404. Mounting holes 420 are provided inthe plate 402, for mounting a camera onto a plate 402. As shown in FIG.11, the camera mounting plate 402 is spaced slightly ( e.g., 0.06inches) the top surface 281 of the base plate 272. This providesclearance underneath the plate 402, for camera mounting hardware, andalso suspends the plate 402 above the surface 281, so that it is free tomove in the lateral direction L. The vibration isolator 400 has a lowprofile, with dimension T in FIG. 11 about 0.44 inches.

[0095] In use, the frame 404 is attached to the base plate 272. Thecamera 275 is attached to the camera mounting plate 402 via the mountingholes 420. The front edge F of the isolator 400 is oriented parallel toline H-H (in FIG. 3A).

[0096] Consequently, the plate 402 can move laterally, in the directionL, to dampen vibration of the arms 271 and 273 of the U-section 270.When a shock impulse or vibration occurs on the U-section 270, the baseplate 272 and frame 404 of the vibration isolator 400 will move with thevibration or impulse. However, the camera 275 and mounting plate 402 arelargely isolated from the frame 404 by the suspension of the plate 402within the frame. Consequently, the camera 275 and plate 402 remainsubstantially still, via inertia, as the frame 404 moves under shockimpulses or vibration. Specifically, if, under an impulse or vibration,the frame 404 moves to the right side, the mounting plate 402 remainssubstantially in the same position. The foam 406 on the left sidecompresses dampening the movement. The linear bearings 405 minimizefriction between the frame 404 and the mounting plate 402, so that theplate 402 can move freely left and right within the frame 404,compressing the foam 406, as necessary, to silently dampen shock andvibration. The foam 406, when compressed, provides little return force.Accordingly, the return springs 408 are provided to return the frame 404and mounting plate 402 to relatively centered positions, after the shockimpulse or vibration has passed.

[0097] As shown in FIGS. 3B and 12-14, in an alternative design, a tracksection 500 may be removable from the track section arms 62.Specifically, in the removable design, track tubes 502 are used, similarto the track tubes 162, but with the back ends of the track tubes 502having slots 504. Preferably, a single clamping bolt 506 extends througheach of the track section arms 62 (as shown in FIG. 3B). The clampingbolts 506 pass into the slots 504 in the track tubes as the track tubes502 are installed into the track section arms. The track tubes 502 arefully installed when the end of the slot 504 bottoms out against theclamping bolt 506. The clamping bolts 506 are then tightened, securelyattaching the track section 500 onto the track section arms, and henceto the boom arm 44.

[0098] The track section 500 may be removed by loosening the clampingbolts 506 and pulling the track sections out of the track section arms.

[0099] With the track section 500 removed, the crane 40 is significantlyshorter. This allows the crane to be more easily handled and shipped.The track section 500 may optionally be crated and shipped apart fromthe rest of the crane. As a result, the maximum dimension of the crane40, for shipping purposes, is greatly reduced. The shipping weight maythen also be divided between the track section (optionally including thecamera frame 68 ) and the rest of the crane 40.

[0100] The track section may be more permanently attached to the boomarm 44 in the design shown in FIGS. 1-6, using the track section 60, orit may be removable, using the track section 500 shown in FIG. 13. Withthe track section removable, other accessories may be attached to theboom arm 44 in place of either track section 60 or 500. For example, ashort camera platform or plate 530, as shown in FIG. 17, may be attachedto the boom arm 44, via square tube stubs 532 inserted into the squareopenings 174 in the track section arms 62. Similar accessories, such asrisers, drop down fixtures, swing heads, etc. may alternatively beattached and removed from the boom arm 44, in the same way that thetrack section 500 is attached and removed. For some applications, theversatile movements provided by the track section 60 or 500 are notneeded. For these applications, the track section can be temporarilyreplaced with one of the smaller and lighter accessories describedabove, providing a more compact and lightweight crane. Due to the 2:1ratio of the front and rear sections of the boom arm, every kilogramremoved from payload (which here includes the track section or otheraccessory, as well as the camera and camera frame), reduces thecounterweight load by two kilograms. Consequently, every one kilogramreduction in payload reduces the total crane weight by 3 kilograms.Hence, in some applications, replacing the track section 60 or 500,along with the camera frame 68 or 280 supported on the track section,can significantly reduce the total weight of the crane.

[0101] Referring still to FIGS. 12-14, a mounting block 520 isadvantageously provided to allow the track section 500 (along with thecamera frame 68 supported on the track section 500 ) to be attached toother types of camera cranes or dollies. The mounting block 520 has tubeopenings 522 adapted to receive the slotted back ends of the track tubes502, similar to the openings in the track section arms 62. The mountingblock 520 also has clamping bolts 526 for securely attaching the tracktubes 502 to the mounting block 520, in the same way that the tracktubes 502 are attached to the track section arms, as described above.With the track tubes attached to the mounting block 520, back ends ofthe track tubes are held in alignment.

[0102] The mounting block 520 is therefore preferably attached to thetrack tubes 502, during shipping, to hold the track tubes 502 in place.The mounting block can also be used to attach the track section to othertypes of cranes or dollies. A mounting hole 524 in the mounting block520 allows a mounting bolt to extend through the mounting block, toattach the mounting block 520 and the track section 500 onto a platformor surface of another crane, such as the cranes described in U.S. Pat.Nos. 5,318,313; 5,312,121; or 5,781,814, incorporated herein byreference.

[0103] Turning now to FIGS. 15 and 16, an accessory 600 for providingroll movement is attachable to the back surface 606 (or the frontsurface 608) of the base plate 272. The roll movement accessory 600 hasa base plate bracket 602 preferably joined to the back surface 606 ofthe base plate 272 via bolts 604. An end plate extends verticallyupwardly from the base plate bracket 602 and supports a hand grip jointor motion control device 276 having the construction and operation asdescribed above. A hand grip 274 extends back from the hand grip joint276. A roll end plate 622 is attached to the hand grip joint 276. A rollplatform 620 extends forward (or away) from the handgrip joint 276. Thecamera 275 is mounted on the roll platform.

[0104] As described above with reference to FIGS. 1-6, the base plate272 can be moved in many ways. However, it cannot roll. FIG. 8 shows anembodiment which can add a limited roll movement. The accessory 600shown in FIGS. 15 and 16, when attached to the base plate shown in FIGS.1-6, also provides roll movement. However, it is more compact, simpler,and more versatile than the roll embodiment in FIG. 8.

[0105] In use, the roll accessory 600 is bolted onto the base plate 272,and may be installed only when roll camera movement is needed. Thecamera 275 is then attached to the roll platform 620. The hand grip 274is preferably behind the camera 275 and roll platform 620, as shown inFIG. 16. The hand grip 274 and hand grip joint or motion control device276 are then operated as described above with reference to FIGS. 1-6.The roll platform 620 carrying the camera 275 is rolled to the desiredangle. The hand grip joint 276 is tightened down to the desired amountof drag. The center of gravity of the camera 275, the roll platform 620,and the roll end plate 622 is preferably set up so that the entirepayload is balanced about the roll axis L-L in FIG. 16. If balanced,then even with zero drag force applied by the hand grip joint 276, thecamera will remain in whatever roll position it is placed into. Minorimbalances may also not be noticeable due to residual drag or frictionin the joints. The camera lens 277 may also preferably be positionedco-linear with the roll axis L-L, so that the recorded image appears torevolve a stationary center point as the roll angle of the camerachanges with pivoting or rotating movement of the roll platform 620.

[0106] With smaller cameras, the accessory 600 can provide a continuous360°+roll movement. With larger cameras, the roll movement may belimited due to the camera or film magazine contacting the arms 271 or273 of the U-frame section 270. However, in most filming situations,roll movements beyond 15-30° from vertical are not needed.

[0107] In certain filming or video applications, it is advantageous tochange the ratio of the boom arm 44. This ratio is determined by theratio of the distance between the boom arm front pivot joint 64 to theboom arm center pivot joint 46, to the distance between the boom armcenter pivot joint 46 and the boom arm rear pivot joint 54. In the boomarm embodiment shown in FIG. 3A, this ratio is 2:1. FIGS. 18 and 19 showan alternative boom arm 700, which is extended to provide added reach tothe camera crane. The boom arm 700 shown in FIGS. 18 and 19 is the sameas the boom arm 44 shown in FIG. 3A, except as follows.

[0108] The second front segment 84 of the boom arm 44 is severed,separating the first front segment 82 from the rest of the second frontsegment 84, with an extension section 702 installed between the sections82 and 84, as shown in FIG. 18. The extension section 702 has the sameexterior shape and dimensions as the second front segment 84. Cornerpins 704 extend from the corners of the extension section 702 intocorner bores 706 in the section 84. Similarly, corner pins 704 extendfrom the modified first front segment 82 into corner bores 706 in theextension section 702.

[0109] An arm connecting plate 708 is secured within the front segment82 via arm plate bolts 710. The back end of the arm connecting plate 708extends outwardly from the segment 82 into the extension section 702. Apair of extension section locking bolts 724 extend from the top throughthe bottom of the extension section 702. A slot in the front end of thearm connecting plate 708 is positioned around the extension lockingbolts 724. The arm connecting plate 708 extends vertically from thebottom inside surface 709 to the top inside surface 711 of the section82, preferably, with a line to line fit. The section 82 is attached andsecured to the extension section 702 by aligning the corner pins 704with the corner bores 706, and then sliding the two sections together.Correspondingly, the slot in the front end of the arm connecting plate708 moves into the extension section 702, around the extension lockingbolts 724. The extension locking bolts 724 are then tightened, clampingthe arm connecting plate 708 and the section 82 to the extension section702. As the arm connecting plate 708 fits closely within the interiorlower and upper surfaces 709 and 711 of the extension section 702,slight compression of the extension section 702 by the extension lockingbolts 724 securely clamps the extension section 702 and the frontsegment 82 together.

[0110] The extension section 702 is similarly attached to the modifiedsecond front segment 84. Specifically, an extension connecting plate 720is secured within the extension section 702 by bolts 722. The extensionconnecting plate 720 preferably fits substantially line-to-line with thelower and upper interior walls 709 and 711, of both the extensionsection 702 and the modified second front segment 84. The back end ofthe extension connecting plate 720 extends rearwardly out of theextension sections 702 and into the segment 84. Arm locking bolts 714extend from the top to the bottom of the segment 84. A slot in the frontend of the extension connecting plate 720 fits around the arm lockingbolts 714.

[0111] The extension section 702 is attached to the segment 84 byaligning the corner pins 704 on the extension section 702, with thecorner bores 706 in the segment 84, and sliding the extension section702 against the segment 84. Correspondingly, the front end of theextension connecting plate 720 slides into the segment 84 and around thearm locking bolts 714. As the bolts 714 are tightened, the front end ofthe segment 84 compresses sufficiently to securely lock the extensionsection 702 to the segment 84. In practice, the extension section 702 ispreferably attached first to the segment 84, and then the front segment82 is attached to the extension section 702, for ease of assembly.

[0112] The extension section 702 is an accessory which may or may not beused. When used, it is installed to extend the length of the arm, asdescribed above. The extension section 702 may be stored and shippedseparately from the arm 700, to reduce storage and shipping containersize. When the extension section 702 is not installed or used, the endsegment 82 is connected directly to the second front segment 84. Inparticular, the corner pins 704 in the end segment 82 are aligned withthe corner bores 706 in the segment 84, and the two segments are broughttogether. As this occurs, the front end of the arm connecting plate 708moves into the interior of the segment 84. The slot in the armconnecting plate 708 moves around the arm locking bolts 714. The armlocking bolts 714 are tightened, to secure the segment 82 onto thesegment 84, to provide a boom arm substantially the same as the arm 44shown in FIG. 3A (but adapted to be extendable via use of the extensionsection 702). The extension section 702 can be of any desired length.Typically, the extension section 702 is between 0.5-4 foot, morepreferably 1 or 2 feet long.

[0113] As use of the extension section 702 lengthens the boom arm 700,in comparison to the boom arm 44, the leveling rods 48 must belengthened by a corresponding amount. As shown in FIGS. 20 and 21, anextended leveling rod 730 includes an extension rod 732 having anextension connection collar 734. The collar 734 is preferablypermanently attached to the extension rod 732, via a pin 736, welding,etc. The leveling rods 48 shown in FIG. 3A are converted to be adaptablefor use with an extended arm by severing the front end of the levelingrod 48 just behind the front pivot joint 66. A rod end collar 744 ispreferably permanently installed to the rod end 742 having the pivotjoint 66. The rod end collar 744 is dimensioned to slide into theextension rod 732. Similarly, the extension connection collar 734 isdimensioned to slide into the rear segment of the leveling rod 48. Afirst quick release locking pin 740 extends through a locking pin hole738 in the extension rod 732 and the rod end collar 744. This allows therod end 742 to be quickly connected and disconnected from the extensionrod 732. Similarly, a second quick release locking pin 740 extendsthrough a locking pin hole 738 in the rear segment of the leveling rod48 and the extension connection collar 734. This allows the extensionrod 732 to be quickly and easily attached and removed from the levelingrod 48.

[0114] In use, a pair of extension rods 732 matching the lengths of theextension section 702 to be used are provided as a kit. The extensionrods 732 are installed to provide extended leveling rods 730 matchingthe increased length of the arm 700 provided by the extension section702. The extension rods 732 are installed by inserting the extensionconnection collar 734 into the back segment of the leveling rod 48 andsecuring them together with the locking pin 740. The rod end 742 is thensimilarly attached into the front end of each extension rod 732.

[0115] When the extension rods 732 are not used, the rod end 742 isconnected directly into the back segment of the leveling rod 48 byinserting the rod end collar 744 into the leveling rod 48. The rod end742 is secure in place with a locking pin 740. When an extended boom armis used, additional counterweights are used to maintain the arm inbalance. The counterweight platform at the back end of the arm maytherefore be enlarged to carry more counterweights, as needed.

[0116] The track section 60 shown in FIGS. 1-3B may advantageously beused in certain applications separate from the boom arm 40. For example,the movement features provided by the track section 60 may beadvantageously used by attaching the track section 60 directly to thedolly platform 28 (without using the other components of the crane 40).In this way, the track section 60 may be provided as an accessory foruse directly on a camera dolly, such as the dolly 20 shown in FIG. 1, orwith other camera dollies or cranes. Referring to FIGS. 22-24, a tracksection accessory 800 includes the track section 60 shown in FIGS. 1-3B.The slider plate assembly 70 is not used. Rather, a slide head 820 isprovided on the track section 60. The accessory 800 is attached to acamera dolly platform, or other support, via a track frame 802.

[0117] Referring momentarily to FIGS. 25-27, the track frame 802, usedto attach the track section 60 to a dolly or crane platform, includes apair of track tube clamp assemblies 808 attached to a base plate 804. Alarge mounting stud 806 extends down from the base plate 804, to securethe base plate 804 and the track frame 802 to e.g., a camera platformsuch as platform 28 shown in FIG. 1. The square track tubes 162 of thetrack section 60 fit within the track tube clamp assemblies 808. Eachclamp assembly 808 includes a clamp plate 814 pivotally attached to aclamping screw 812. The clamping plate 814 clamps the track tube 162within the clamp assembly 808 by turning a hand wheel 810. Clamp platescrews or pins 816 help to maintain the clamp plate 814 in alignment.The clamp plate screws 816 may be spring loaded.

[0118] Turning to FIGS. 28-30, the slide head 820 includes a cameramounting for a Mitchell mount or plate 822 attached to a head plate 828via posts 824. The head plate 828 is slidably attached to the trackbearing rails 164 via slide bearings 826. One or more slide brakes 830on the head plate 828 are used to adjust the sliding friction of theslide head 820 on the track tubes 164. A plate mounting stud 834 on thehead plate 828 is secured to a tube plate 838 via a nut 836.

[0119] Referring once again to FIGS. 22-24, the track section accessory800 is installed onto a platform 28 or other support using a nut on thestud 806. A camera, such as the camera 275, is mounted onto the plate822, via the well-known Mitchell mount design, or other techniques. Theslide head 820 carrying the camera can then slide along the tracksection 60, as described above. The slide head 820 can pass through thetrack frame 802, as shown in FIG. 22. Consequently, the track section 60may be centered on the track frame 802, or it may be offset to one side.For example, as shown in FIGS. 23 and 24, the track frame 802 is at theextreme left end of the track section 60. This provides a maximum amountof travel distance from the platform 28 or other structure supportingthe accessory 800. The slide head 820 may alternatively be inverted onthe track section 60, as shown in dotted line in FIG. 23, to support thecamera underneath the track section 60.

[0120] Consequently, via the use of the track frame 802 and slide head820, the track section 60 provided on the crane 40 as shown in FIGS.1-3B may also achieve several advantages provided by the crane 40, butin a more compact form, which is easier to store, transport, and use inmore confined spaces.

[0121] A novel camera crane has been shown and described. As the crane40 is a single piece, it can be quickly set up, without tools. As itprovides for many different movements, separate leveling heads or otheraccessories are not needed. In addition, the camera operator hascomplete control of all needed camera movements. The crane, which islightweight due to hollow beam construction, undercutting, andlightening holes, can therefor be operated by a single person. Variouschanges and modifications may of course be made without departing fromthe spirit and scope of the invention. The invention, therefore, shouldnot be limited, except by the following claims, and their equivalents.

What is claimed is:
 1. A camera crane comprising: a post assembly; aboom arm pivotably connected to the post assembly; a counter weightplatform pivotably connected to a second end of the boom arm; a tracksection arm pivotably attached to a first end of the boom arm; aleveling rod pivotably attached to the counter weight platform and tothe track section arm; a track section attached to the track sectionarm; and a camera frame linearly movable along the track section, withthe camera frame including a base plate for supporting a camera.
 2. Thecamera crane of claim 1 further comprising a track axle pivot jointpivotably attaching the camera frame to the track section, and allowingthe camera frame to pivot about an axis perpendicular to linear movementalong the track section.
 3. The camera crane of claim 1 furthercomprising a hand grip joint pivotably attaching the base plate to thecamera frame, to allow a tilt up/down movement of the base plate, forchanging the elevation angle of a camera on the base plate.
 4. Thecamera crane of claim 3 wherein the center of gravity of the camera iscoaxial with the hand grip joint.
 5. The camera crane of claim 1 whereinthe crane arm has a rear segment, and first, second, and third frontsegments, with the rear segment joined at a positive rise angle to thirdfront segment, and with the second front segment joined to the thirdfront segment at a run angle equal to the supplement of the rise angle,so that the second front segment extends in a direction parallel to therear segment, and with the first front segment joined to the secondfront segment at a negative rise angle equal and opposite to thepositive run angle, so that the second front segment is at a verticalheight greater than or equal to the height of the other segments, whenthe boom arm is horizontal.
 6. A camera crane comprising: a boom arm; atrack section attached to a front end of the boom arm with the tracksection having track bearing rails having a convex radius of curvatureR; and a camera frame movable along the track bearing rails.
 7. Thecamera crane of claim 6 wherein the radius of curvature R is selected tocompensate for changing deflection of the boom arm as the cameraplatform is moved to different positions along the bearing rails, sothat the lens of a camera on the camera platform remains substantiallyhorizontal, regardless of the position of the camera platform on thebearing rails
 8. A camera crane comprising: a first section and a secondsection; a pivot joint pivotably connecting the first section and thesecond section, with the pivot joint comprising: a tensioner on an axle,with the first section pivotably supported on the axle; an arm plateattached to and pivotable with the first section, the arm plate havingan inner ring section around the axle; a flex plate between a firstsurface of the inner ring section of the arm plate and the tensioner;and a low friction ring between the flex plate and the first surface ofthe ring section of the arm plate.
 9. The camera crane of claim 8wherein the first section is a boom arm and the second section is a postassembly.
 10. The camera crane of claim 8 further including acompression washer between the tensioner and the ring section of the armplate.
 11. The camera crane of claim 10 further comprising a needlethrust bearing between the tensioner and the compression washer.
 12. Thecamera crane of claim 8 wherein the tensioner comprises a hand knobthreaded into the axle.
 13. The camera crane of claim 8 furtherincluding an axle hub around the axle, a receiving groove in the axlehub, and a low friction ring held into the receiving groove by a second